*5.3.2 Equipment cost and maintenance*

Generally, spraying equipments in use are often in poor conditions due to lack of proper maintenance and the cost of buying original of these equipment or their parts is expensive for majority of these farmers. As reported by Abhilash and Singh [27] a large number of farmers never change sealing washers in their equipment and this is equally true for Cameroon, where most farmers share equipment without any maintenance knowledge on these equipment besides controlling the nozzles for faster application which does not necessarily lead to efficiency.

#### *5.3.3 Repackaging or no labeling/or labeling in different languages*

In Cameroon, using of pesticides without labels is a practice by vendors for selling banned products [21, 26]. In some cases, repackaging of pesticides in small quantities is to meet customer's demand due to the high cost in purchasing the entire container that is usually more than the amount required, thereby resulting to packaging in smaller containers without labels.

There are also products that are package in the Chinese and French, with little or no English language making it difficult for the farmers to follow the instructions and without proper guidance on usage there is bound to be malpractice.

#### *5.3.4 Weather conditions*

In order to maximize the best results possible from pest control mechanisms, accurate timing in pesticides application is paramount [27]. Unfortunately, Cameroon does not have reliable meteorological stations to provide farmers with information related to weather conditions and this situation has been compounded by the changing climates. This makes it difficult for small-scale farmers to accurately apply insecticides in a timely manner that will be most beneficial for plant growth. According to Balasha and Nsele [28], about 60% of farmers apply insecticides during the early mornings and late evenings from about 4–6 pm, with a handful applying irrespective of the time as it is the case observed in Wotutu area where farmers apply more pesticides after the rainfall had washed the previous pesticides about an hour after application.

#### *5.3.5 Inappropriate concepts and economic pressure*

In Cameroon, farming is looked upon as the last resort for many people especially cultivation of vegetables like tomatoes, cucumbers, and watermelons so as to make some fast profit. Yet in order to achieve optimum results these respective endeavors it requires mastery, so most Cameroonians believe more utilization of pesticides and chemicals automatically translates to high yields; thereby overreliance and abusive use of pesticides is practiced, as it is the case reported by Tarla et al. [24] that pesticides use does not always adhere to recommended safe practices [29].

Any desired results with regards to pesticides can only be guaranteed by properly respecting the guidelines of the producer and timing too is of the essence. Unfortunately application methods still depends on many variables such as the

nature of the insecticide, its formulation, pests to be controlled, application site, water availability and training of the farmer, without of any these factors in place malpractice is most likely to occur.

## **6. Intoxications resulting from malpractices**

Intoxications or poisonings resulting from insecticides are mainly the result of malpractices at the level of agrochemical companies, retailers, and farmers [24, 30]. Highest poisoning cases reported for Littoral and followed by South West Region. These are then followed by North West, West and Centre Regions while the least is from the Northern Regions (Adamawa, North and Extreme North). Highest cases from Littoral and South West is not surprising because very large cocoa and banana plantations are found in these Regions and these two crops are noted for their intensive use of pesticides especially insecticides and fungicides. In addition, there are also many vegetable farmers who cultivate to meet the demands of Douala—the economic capital found in the Littoral Region and near to the South West Region. To have high yields and high quality crops, these farmers use much insecticides and therefore possibilities of misuse and ultimately intoxications.

The crops most implicated for these poisonings are tomato, cotton, banana, cabbage, lettuce, onion, African nightshade, and cocoa while the most implicated insecticides are terbufos (Class Ia), ethoprofos (Class Ia), cypermethrine (Class II & III), chlorpyriphos-ethyl (Class II), combination of lambda cyhalothrine & imidacloprid (Class II). Although the signs/symptoms of intoxications vary with the different implicated active ingredients, the common signs and symptoms of acute intoxications reported are vomiting, abdominal pain, diarrhea, skin irritations, headaches, blurred visions, convulsions as well as rare cases of immediate death, most of which are accidental and occupational. The most common routes of exposure is the skin and respiratory tract. Most of the health personnel have no training or knowledge on recognizing and managing intoxications. From their responses, except for one case of suicide attempt, all cases of intoxications mentioned in the health centres or hospitals are accidental.

#### **7. Alternatives to the use of synthetic insecticides**

Apart from their cost, pesticides have a significant impact on human health, wildlife (terrestrial and aquatic) and the environment (soil and water pollution, etc.). Pesticides are often of poor quality or illegal, due to the low level of control of sales and distribution channels, and are generally misused because farmers are poorly trained in their use and have little knowledge of pest biology and ecology. Cameroon produces several agricultural commodities for export and domestic consumption hence this has increased the rate of application of inputs such as pesticide to help protect the crops from pests and diseases. Chemicals continue to be the main tools to protect crops during field and storage in spite of the deleterious effects as a result of malpractices.

Generally, the pest management practices reported by researchers and farmers include mainly use of synthetic pesticides and their alternatives such as cultural practices, botanical pesticides, use of biological control agents and the use of resistant/tolerant varieties. Of all the alternative pest management techniques, cultural practices and use of plants with insecticidal properties are the most common. Use of botanical insecticides is very common for cocoa, tomatoes, and stored products (e.g. maize, beans, cowpea). Sanitation, manual weeding, use of traps, and pruning are

#### *Insecticide Use and Application in Cameroon DOI: http://dx.doi.org/10.5772/intechopen.102634*

the most common cultural practices for field crops while use of containers with tight-fitting lids or bags is most common practice to protect stored products such as grains of maize, beans and cowpea.

In Cameroon, farmers depend on the use of synthetic insecticides to reduce crop losses due to insect pest, increase crop production, and urge to meet up with the high demand for agricultural products [25, 31]. However, over dependence and inappropriate applications of synthetic insecticides has led to harmful effects on the environment and human health [32]. These effects are numerous such as disruption of the normal functioning of the ecosystem, toxicity for a wide range of non-target organisms including humans and a high tendency to accumulate in the environment [33]. In addition to these, there is also the problem of pest ecological backlashies such as resurgence, replacement, and resistance. Most insecticides easily become ineffective due to the development of resistance by the insect pest. In order to minimize or completely eliminate the challenges posed by these chemicals, many researchers have carried out a number of researches in an attempt to find sustainable alternatives to replace synthetic insecticides [32]. Numerous efforts have been undertaken by IRAD, CARBAP, Universities and some International organizations like IITA and CIRAD to search and evaluate efficacies and effectiveness of alternatives to synthetic insecticides for the management of insect pests. Alternatives to synthetic insecticides include techniques such as:


#### **7.1 Cultural control methods**

Cultural techniques for pest management involves the manipulation of the environment or implementation of preventive practices with the aim to reduce pest population and their damages [32].

#### *7.1.1 Intercropping*

This is the practice of increasing crop diversity by growing more than one plant species in close proximity in a field to overcome insect pest outbreaks associated with monocultures [34]. Tanyi et al. [35] used this system of intercropping beans and maize together with use of extracts of Piper spp. to manage fall army worm in the Buea municipality. Most smallholder farmers have diverse cropping systems and therefore do not have much insect pest problem.

#### *7.1.2 The use of Insect resistant plant varieties*

Although the use of synthetic pesticides is usually effective, most pesticides easily become ineffective due to the development of resistance by the weevils or insects [32]. Cultivation of plant varieties which are resistance to insect attack minimizes the need for insecticide applications [32, 34]. For cocoa, resistant/ tolerant varieties used are IMC60, Catongo Trinitario, Playa Alta2, SIC5, SNK614. For tomato, use of improved or tolerant varieties such as Dona F1, Heinz 1370, Fline Mecline and Mobo line. For bananas/plantains, use of tolerant varieties such as CRBP 039, FHIA 21. For cotton, use of Bt-Cotton, use of tolerant/resistant varieties such as NGT115, SARC-1-57-2, KVX-165-14-1, LORI, IT97K-556-6-IITA. The use of resistant/tolerant varieties such as the local variety VYA-Cowpea.

## **7.2 Biological control methods**

Biological control is an environmentally sound and effective means of reducing or mitigating pests and their effects without having to spray the plant with chemical insecticides but rather through the use of natural enemies. Biological control agents of insect pests are in three groups namely; predators, parasitoids and pathogens. There are three primary methods of using biological control agents in pest control programs which are the importation, augmentation and conservation methods.

#### *7.2.1 Entomopathogens*

Although not widely applied on agro-ecosystems in the country, some entomopathogens have been evaluated on research stations/sites. *Trichoderma* spp. has been used in the biological control of cocoa brown rot caused by *Phytophtora infestans* while endophytes have been evaluated for crop protection purposes [36– 38]. Pathogenic organisms such as entomopathogenic fungi (*Beauveria bassiana* and *Metarhizium anisopliae*), entomopathogenic nematodes (*Steinernema* spp. and *Heterorhabditis* spp) and endophytes (nonpathogenic *Fusarium* spp) have been tested against *Cosmopolites sordidus* (banana borer weevil) [32]. After the application of these biological agents, results revealed that entomopathogenic fungi and nematodes are effective in controlling adult weevils while endophytes effectively control the immature stages of the pest mainly at the level of the laboratory/shade houses [32]. Emamactine benzoate and oxymatrine are used for stem borer and fall army worm (caterpillars) management on maize while sex pheromones are sometimes used to capture and kill adult moths. For cotton, emmamectine benzoate, spinosad are used to control the cotton bollworms (*Helicoverpa armigera*). *Metarrhizium anisoplae* used on flower bud thrips on cowpea.

#### *7.2.2 Predators and parasitiods*

In banana/plantain farms, some farmers encourage the trap-jaw ant (*Odontomachus* spp) as they are convinced these have excellent searchability and feed on eggs, larvae and pupae of *C. sordidus*. In the Northern regions, where majority of the cotton farms are found, they encourage and promote survival of natural enemies: parasitoids such as *Pediobius vigne*,*Trichogramma*, *Schixopyrannus* and predatory mites used for the management of caterpillars on cotton. The weaver ants (*Oecophylla longinoda*) are usually conserved by some cocoa farmers to help reduce the population of cocoa capsids (mirids).

#### **7.3 Plants with insecticidal properties**

Several plants with insecticidal properties (mortality, repellence, development disruptor, feeding and oviposition deterrence) have been identified and their efficacies tested in the laboratory and fields. A total of 29 plant species reported as plants having some pesticidal properties and use for one or more different pests and diseases. Based on journal publications on insecticidal plants in the country, there are 29 plant species belonging to 21 different plant families of which Fabaceae

(19.1%), Amaryllidaceace (19.1%), and Meliaceae (14.3%) were the most reported. Most common parts used are seeds and leaves mainly as extracts or dry powders. These insecticidal plants are usually applied in the form of ash, essential oils, powder formulations and aqueous or alcohol extracts.
